[X86] Introduction of FeatureX87.

Add FeatureX87 in X86 backend to be able to define CPUs which doesn't have x87.

Differential Revision: http://reviews.llvm.org/D13979

llvm-svn: 264148
diff --git a/llvm/lib/Target/X86/X86Subtarget.cpp b/llvm/lib/Target/X86/X86Subtarget.cpp
index 6e72a4e..7f4dfe7 100644
--- a/llvm/lib/Target/X86/X86Subtarget.cpp
+++ b/llvm/lib/Target/X86/X86Subtarget.cpp
@@ -239,6 +239,7 @@
 void X86Subtarget::initializeEnvironment() {
   X86SSELevel = NoSSE;
   X863DNowLevel = NoThreeDNow;
+  HasX87 = false;
   HasCMov = false;
   HasX86_64 = false;
   HasPOPCNT = false;